BackgroundAvocado (Persea americana) is one of the plants widely used in ethnomedicine in Nigeria. The present study was aimed at investigating effects of aqueous Avocado (Persea americana) leaf extract on total cholesterol, triacylglycerols, protein and haematological parameters in carbon tetrachloride (CCl4)-intoxicated rats.MethodsWe evaluated the possible effects of pre-treatment with aqueous extract of Persea americana (AEPA) on protein, total cholesterol (T-CHOL), triacylglycerols (TAGs) and haematological parameters in Wistar male albino rats intoxicated with CCl4. Group 1 was the healthy control; group 2 rats were pre-treated with Reducdyn® (100 mg/kg/day) as a standard drug, groups 4 and 5 rats were pre-treated with AEPA at a dose of 100 mg/kg and 200 mg/kg per day respectively, the treatments were administered orally for 7 days. On the seventh day, rats in the treatment groups were injected with a fresh mixture of CCl4 and olive oil (3 ml/kg, 1:1; sc).ResultsPre-treatment of rats with AEPA resulted in marked increase (p < 0.05) in total protein and reduction in T-CHOL (19–34%) compared to CCl4 alone. Also, there was significant decrease (p < 0.05) in serum TAG concentration when rats were pre-treated with 100 mg and 200 mg kg− 1 b. wt. AEPA. Similarly, AEPA provoked (p < 0.05) a lowering of T-CHOL and TAG levels and an increase in liver protein concentration in the rats. Administration of AEPA at both concentrations restored (p < 0.05) WBC count and ameliorated neutropenia and lymphocytosis caused by CCl4 intoxication.ConclusionThese results suggest that AEPA could be protective against the development of fatty liver and might also be exhibiting the potential to prevent alterations in haematological parameters caused by CCl4 intoxication in rats.